It is meant to
end the debate about the
importance of penis size to women.

It is especially
meant for men suffering from Penile Inadequacy
Anxiety Syndrome (PIAS), which symptoms are:

persistent worries that your penis is smaller than those of other men

obsessive thoughts about the role of penis size in women's sexual satisfaction

sexual inferiority complex with a phobia for rejection.

It is aimed at the heterosexual man.
PIAS is a condition that affects mainly heterosexual men, because
symptoms 1 and 2 don't apply to them:

Gay men
usually know where they place on the size-scale because they generally
have plenty of occasions to compare. In contrast, straight men have
no true-life reference and feel often mislead by the contradictory
statements of women.

Just as
for women, there is no secrecy to gays about the importance of penis
size. Straight men are the ones being left in doubt about how they compare
and about whether or not bigger is better.